Recently, in line with the trend toward high-quality fiber products, various types of functional fibers have been marketed. In an effort to meet the trend, research into heat-storing and retaining fibers and the technical development thereof has been actively conducted.
In connection with this, European Patent No. 302141 discloses a heat-storing and retaining polyester fiber which contains fine zirconium carbide particles. However, fine zirconium carbide particles have a disadvantage in that they cannot provide fabric products having various colors because they take on a gray or black color when being incorporated into blended yarns.
Furthermore, Japanese Unexamined Patent Application Publication No. Hei 3-69675 discloses a method for producing a staple fiber by kneading 40 wt % of a fine ceramic powder, such as zirconium oxide, silicon oxide, aluminum oxide or the like, to prepare master chips, mixing the master chips with regular chips to obtain a mixture, and spinning the mixture. However, although the staple fiber has good whiteness, it has a disadvantage in that the production of filaments is difficult because the dispersibility of a large amount of ceramic particles is poor.
Furthermore, Korean Patent Application Publication No. 10-1995-020757 discloses a method for producing a far-infrared polyester fiber, the method including: mixing at least two or more types of fine far-infrared ceramic powders to obtain a mixture, adding 0.5-9.0 wt % of the mixture to a polymer; preparing a slurry of ethylene glycol by using a high-speed mixer; introducing the slurry into an ester reaction tube; and kneading the introduced slurry. The method has a problem in that the method causes the abrasion of polymerization, spinning and post-processing apparatuses and various types of guides because a main component is a zirconium oxide-based material and thus has high hardness.
Furthermore, Korean Patent No. 0926588 discloses a method for producing a spun yarn, the method including: uniformly mixing Cs0.33WO3 with a polyester resin to prepare master batches; mixing, melting and spinning the master batches; elongating the master batches to prepare a multi-filament fiber; and cutting the multi-filament fiber into staple fibers. However, the present method has disadvantages in that the method can be used only for the preparation of a spun yarn because the dispersion of the additive is poor and in that a heat-storing and retaining effect is present but the persistence thereof is poor due to the characteristics of the additive.